Lifting-jack.



M. L. JENKINS.

LIFTING JACK. APPLICATION FILED SE PT. l0 1908.

Patented Dc.24, 1912.

3 SHEETS-$111351 l.

Patented Dec. 24, 1912.

3 SHEETSSHEET 2.

WITNESSES v INVENTOR COLUMBIA FLANOURAPH c0.,wAsH|NaTON. D; c.

M. 'L. JENKINS.

LIFTING JAUK.

APPLIOATION FILED SEPT.10, 1908.

1,048,077. Patented D60.24,1912.

3 SHEETS-SHEET 3.

b O In? COLUMBIA PLAuUGlZ/Hli Lu. WASHINGTON, u c.

1 UNITED STATES PATENT OFFICE. j Y

MERRILL L. JENKINS, or HARVEY, ILLINOIS, nssreivoza T0 THEBUDA COMPANY, 01?

CHICAGO, ILLINOIS, CORPORATION OF ILLINOIS.

LIFTING-JAOK.

Application filed September 10, 1908.- Serial No. 452,428.

Specification of Letters Iatent.

I Patented Dec. 24,1912.

To all whom it may concern:

Be it known that I, MERRILL L. JENKINS, a citizen of the United States, residing at Harvey, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Lifting-Jacks, of

which the following is a specification.

The invention relates to lifting jacks of the pawl and ratchet type, and has for its object; the provision of an improved form of operating mechanism for the lifting and holding pawls. One embodiment of the invention is illustrated in the accompanying drawings, wherein Figure 1 is a side elevation of the jack with the cover plate removed, the parts being in position for raising a load,

Figure 2 is a view similar to that of Figure 1, but with the operating mechanism for the pawls reversed for lowering the load, and the pawls in the position occupied when the actuating lever is raised, and

Figure 3 is a view similar to that of F igure 2, but with the pawls in the position occupied when the actuating lever is lowered.

Referring to the drawings, the principal parts of the mechanism may be enumerated as follows, 1 is the body or framework of the jack, 2 is the lifting bar provided with the usual rack 3, 4 is the operating pinion for the rack 3, which pinion is carried by the shaft 5 journaled in the framework, 6 is an operating gear or 'ratchetkeyed to the shaft 5, 7 is the actuating lever which is pivoted member or plateslidably. mounted upon the face of the frame, 13 is the reversing handle for'moving the reversing plate 12, which handle is provided with an eccentric fitting in a recess 14 in such plate, and pivoted to the frame at 15, 16 and 17 are abutments or cams pivoted to the reversing plate 12 at 19 and 20 respectively, and 21 is an operating cam for the holding pawl 11, which cam guided by the strap 21, is provided with a connecting rod 22 pivoted at its lower end at 23 to the actuating lever. The pawls 9 and 11 are normally held in engagement with the ratchet 6 by means ofthe springs 24'and 25, and the members 16 and 17 are normally held in the position shown in Fig.

1 by means of the springs 26 and 27. I The springs 24: and 25 are secured to the pawls 9 and 11 by means of the studs 28 and 29 respectively, which studs extend laterally from. the pawlsin position to engage the ends ofthe cams 17 and 21 when the mechanism is in lowering position. i 1

In the raising operation the parts occupy the position shown in Figure 1, and upon .1 the actuation of the handle the lifting pawl 9 advances the ratchet 6 step-by-step and the holding pawl 11 maintains the ratchet in "its various positions until the pawl'9 is lowered to engage another tooth upon the r L ratchet. It will be noted that during this raising operation none of the mechanism carried by the reversingplate 12 is brought into operation, and that the pawls 9fand 11 are yieldingly held in engagement with the ratchet 6bythe springs 24 and 25. Figure 2 illustrates the'position of the parts when the mechanism has been reversed forthe lowering operation. This reversal of the operating parts is secured by shifting the handle 13 from the position shown in Figure 1 to that of Figure 2, which movement carries the reversing plate 12 to the right and brings the cam members 16 and 17 to such position that they mayooti'perate withfthe studs 29 and 28 carried respectively by the pawls 11 and 9. When the handle 7 is in the position shown in Figure 2 the lifting pawlhas been disengaged during its down ward movement by means of the cam surface on the member 17, and theload issupportedi by the engagement of the holding pawl 11 with one of theteeth of the ratchet 6. If now the handle 7 is moved downward to its extreme position, the parts will occupy the position indicated in Figure 3. At this time the pawl 9 has been moved up such a distancethat its stud 28 passes above the cam surface on the member 17 which movement permits the spring 24L to force the pawl 9 into engagement with one of the teeth of the ratchet. The downward movement of the handle 7 has also carried the cam;mem-' of the member 21. Considerable pressure is applied to the stud 29 before the pawl 11 is released from the tooth, due to the fact that this pawl is sustaining the load and therefore cannot be easily disengaged, so that a quick release occurs when the pawl 9 engages the tooth of the ratchet and moves such ratchet back a suflicient distance to permit the release of the pawl 11. As the handle 7 moves upward from the position of Figure 3, the pawl 9 gradually descends carrying the load upon the ratchet 6, the holding pawl at such time being released. During the downward movement of the pawl 9 the cam surface of the member 17 presses yieldingly against the nose of the pawl but without disengaging because of the pressure exerted upon the pawl by the ratchet 6. hen, however, the cam member 21 has been retracted a sufficient distance to allow the holding pawl 11 to engage a tooth upon the ratchet, the pawl 9 is relieved from the pressure of the ratchet and is forced out to the position shown in Figure 2 by the member 17. On a downward movement of the actuating lever 7 the series of operations just described is repeated. It will be understood that the invention is not limited to jack constructions in which a circular ratchet is employed, but that with slight modifications, the operating mechanism may be applied to a straight rack or ratchet, it being common in the art to apply the lifting and holding pawls either to a jack employing a circular ratchet such as the one illustrated, or to a jack in which the pawls engage directly a rack upon the lifting bar.

Having thus described my invention and illustrated its use, what I claim as new and desire to secure by Letters Patent is the following 1. In a lifting jack, the combination with a toothed member, of an actuating lever, a pivoted lifting pawl on the actuating lever and a pivoted holding pawl both normally engaging the toothed member, abutments carried by the free ends of the said pawls, a pair of independently movably mounted cams yieldingly held in position, and movable supporting means for the cams whereby the cams in one position operate to actuate the said abutments to secure the alternate retraction of the two pawls in lowering.

2. In a lifting jack, the combination with a toothed member, of an actuating lever, a pivoted lifting pawl on the actuating lever and a pivoted holding pawl both normally engaging the toothed member, abutments carried by the free ends of the said pawls, a pair of swinging spring held cam members, a support therefor mounted for movement toward and from the pawls, and means cooperating with the cam members whereby the operation of the actuating lever causes the alternate actuation of the abutments by the cam members and the retraction of the two pawls during the lowering operation.

8. In a lifting jack, the combination with a toothed member, of an actuating lever, lifting and holding pawls mounted respectively upon the actuating lever and frame of the jack and normally engaging the toothed member, a movably mounted reversing member, a pair of abutments carried by the reversing member, and a cam member connected to the actuating lever in position to operate one of the pawls, the reversing member and abutments being so arranged that in one of the positions of such reversing member one of the abutments cooperates with one pawl to retract it as the actuating lever moves in one direction, and the cam member cooperates between the other abutment and pawl to retract such pawl as the actuating lever moves in the other direction.

at. In a lifting jack, the combination with a toothed member, of an actuating lever, lifting and holding pawls mounted respectively upon the actuating lever and frame of the jack and normally engaging the toothed member, a movably mounter reversing member, a pair of abutments carried by the reversing member, and a cam member connected to the actuating lever in position to operate the holding pawl, the reversing member and abutments being so arranged that in one of the positions of such reversing member one of the abutments cooperates with the lifting pawl to retract it as the pawl moves down, and the cam member cooperates between the other abutment and pawl to retract such pawl as the lifting pawl moves reversely.

5. In a lifting ack, the combination wit-h a toothed member, of an actuating lever, lifting and holding pawls mounted respectively upon the actuating lever and frame of the jack and normally engaging the toothed member, a movably mounted reversing member, a pair of spring held abutments carried by the reversing member, and a cam member connected to the actuating lever in position to operate one of the pawls, the reversing member and abutments being so arranged that in one of the positions of such reversing member one of the abutments cooperates with one pawl to retract it as the actuating lever moves in one direction, and the cam member cooperates between the other abutment and pawl to retract such pawl as the actuating lever moves in the other direction.

6. In a lifting ack, the combination with a toothed member, of an actuating lever, lifting and holding pawls mounted respectively upon the actuating lever and frame of the jack and normally engaging the toothed member, a pair of movably mounted abutments, and a cam member operated by the actuating lever in position to operate one of the pawls, the abut-ments being so arranged that when advanced for the lowering operation one of the abutments cooperates with one pawl to retract it as theactuating lever moves in one direction and the cam member cooperates between the other abutment and pawl to retract such pawl as the actuating lever moves in the other direction.

7. In a liftin jack, the combination with a toothed mem er, of an actuating lever, lifting and holding pawls mounted respectively upon the actuating lever and frame of the jack, and normally engaging the toothed member, a movably mounted reversing memher, a pair of abutments carried by the reversing member, and an operating member interposed between one of the abutments and one of the pawls and connected to the actuating lever, the reversing member and abutment-s being so arranged that'in one of the positions of such reversing member one of the abutments cooperates with one pawl to retract it as the actuating lever moves in one direction and the operating member cooperates between the other abutment and pawl to retract suchpawl as the actuating lever moves in the other direction.

8. In a lifting jack, an actuating lever, a lifting pawl carried thereby, a holdlng awl,

a reversing member bodily reciprocab e to MERRILL L. JENKINS.

Witnesses:

O. S. WHIMsDoN, J NO. L. WALKER;

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

